brothers are jealous and seek to rob the youngest of his prize and attempt to murder him.
There are corresponding stories in Grimm's Kinder Marchen. In the "Water of Life" the old king is sick, and the sons go in quest of this water, and only the youngest finds it. On the way home the brothers rob him of it--but in the end all turns out well.
Here is in brief a modern Greek household tale. A king had three sons and a mirror, by looking into which an enemy might be seen meditating mischief. In a high gale the magic mirror was carried away and could not be found; accordingly the three princes set out to endeavour to recover it. At a point in the road there diverged three ways. Each laid his ring at this place, and all agreed to meet there at the termination of a given time. The eldest went one way, squandered his money in riotous living, and was so reduced that he had to become an ox-driver. The second did likewise, and to obtain a livelihood herded swine. The third went on till he came to the cottage of an old woman who took him in, and who had a beautiful daughter. As he saw that she was a knowing old person, he told her what his quest was, and she informed him that the mirror hung in an apple tree